High-power Light Emitting Diodes (LEDs) offer many advantages as sources of illumination as compared to other sources of illumination. For example, LEDs are significantly more efficient than incandescent bulbs. Lighting devices that rely on LEDs as the light source therefore consume significantly less power than an equivalent lighting device having one or more incandescent bulbs as the light source. LEDs also contain no mercury, such as found in compact fluorescent lamps (CFLs). Additionally, lighting devices that employ LEDs as the light source are solid-state devices and therefore more physically robust than incandescent, metal halide, sodium vapor lamps or CFLs. LED-based lighting devices also have a long lifetime, thus requiring fewer replacements as compared to most other lighting sources.
Luminaires can be designed around LEDs to make optimal usage of LEDs' advantages. Merely replacing a metal halide lamp in a streetlight with an LED source, for example, will yield less than optimal results due to the different optical and thermal requirements of LEDs as compared to metal halide lamps. However, there is a significant market demand for retro-fitting existing luminaires with LED sources. Optically, the output from an LED is much more directive and can be utilized best when the optical system is optimized around that characteristic. Thermally, LEDs emit far less heat than most other sources, however, the heat they do emit must be removed effectively in order for the LEDs to operate near their full potential.